Variable throat venturi apparatus for mixing and modulating liquid fuel and intake air to an internal combustion engine

ABSTRACT

Discharge velocity of the air-fuel mixture being supplied through a variable venturi flow passage device to an internal combustion engine is optimized by controllably varying or maintaining area ratio between the throat and exit planes of the device. Opposite jaw faces of the device define the flow passage that is gradually opened and closed in correlation to demand imposed on the engine between idle and full throttle operation. Opening and closing of the jaws are effected by concomitant pivoting of each jaw about separate axes respectively displaced longitudinally in the direction of flow therebetween. By pivoting one jaw on an axis contiguous to or in the vicinity of the throat plane and the other jaw on an axis contiguous to or in the vicinity of the exit plane, any predetermined area ratio or change in area ratio can be preset throughout the operating range of the device.

United States Patent 11 1 Barnes, Jr.

1 1 VARIABLE THROAT VENTURI APPARATUS FOR MIXING AND MDDULATING LIQUID FUEL AND INTAKE AIR TO AN INTERNAL COMBUSTION ENGINE [75] Inventor: Casper William Barnes, .lr.,

Newport Beach, Calif.

[73] Assignee: Dresser Industries, Inc. Dallas Texw 22 Filed: July is, 1974 [21] Appl. No: 489.671

LIN-5,613 11/1912 Roth. v. 26l/D1G 58 1,258,153 3/1918 Shaw,,.............. 261/62 1,542,415 7/1925 Richardson t t 4 261/62 1.555.489 9/1925 Spencer et a1 i t t 4 4 t t i 26l/D1G. 58 2,672,329 3/1954 Zarnack 261/62 1069,1 16 12/1962 MacNeill .1 261/62 1 51 Oct. 7, 1975 3,778 O38 12/1973 Eversole et a1. i i i 261/50 R FOREIGN PATENTS OR APPLICATIONS 141,712 12/1934 Austria 261/62 Primary ExaminerTim Rt Miles Attorney, Agent, or FirmDanicl Rubin [57} ABSTRACT Discharge velocity of the air-fuel mixture being supplied through a variable venturi flow passage device to an internal combustion engine is optimized by controllably varying or maintaining area ratio between the throat and exit planes of the device. Opposite jaw faces of the device define the flow passage that is gradually opened and closed in correlation to demand imposed on the engine between idle and full throttle operation. Opening and closing of the jaws are et fected by concomitant pivoting of each jaw about sep arate axes respectively displaced longitudinally in the direction of flow therehetween. By pivoting one jaw on an axis contiguous to or in the vicinity of the throat plane and the other jaw on an axis contiguous to or in the vicinity of the exit plane, any predetermined area ratio or change in area ratio can he preset throughout the operating range of the device 10 Claims, 7 Drawing Figures U.S. Patent Oct. 7,1975 Sheet 1 of2 3,911,063

U.S. Patent Oct. 7,1975 Sheet 2 of 2 3,911,063

F FIG.7

VARIABLE THROAT VENTURI APPARATUS FOR MIXING AND MODULATING LIQUID FUEL AND INTAKE AIR TO AN INTERNAL COIWBUSTION ENGINE CROSS REFERENCE TO RELATED APPLICATIONS 1. Ser. No. 381,946 filed July 23, 1973 and entitled Variable Venturi Apparatus for Mixing and Modulating Liquid Fuel and Intake Air for Internal Combustion Engines incorporated herein by reference (hereinafter CR-l and 2. Ser. No. 430,808 filed Jan. 4, I974 and entitled Variable Throat Venturi Apparatus for Mixing and Modulating Liquid Fuel and Intake Air to an Internal Combustion Engine incorporated herein by reference (hereinafter CR-2").

BACKGROUND OF THE INVENTION 1. The field of art to which the invention pertains includes the art of internal combustion engines and more particularly to such art as it applies to fuel and air induction systems therefor.

2. In by far the majority of currently used gasoline engines commercially marketed for automotive applications, fuel and air are metered and mixed by a carburetor connected to the intake manifold of the engine. Although these carburetors vary in detail from one manufacturer to the other, they are essentially similar and have over the years been regarded as generally satisfactory in supplying an adequate combustion mix to the engine.

Disclosed in cross referenced application CR-l is an improved apparatus for mixing fuel with air under substantially continuous sonic conditions. The quantity of combustible fuel mix is modulated to meet operating demands of the engine with which it is utilized. Unlike a conventional carburetor, the apparatus of CR-l generally comprises an elongated housing having a central passage defined in a venturi cross section. The passage is located intervening between the edge facings of opposite jaw faces which are supported in a fixed angular relation to each other. Varying the venturi flow area in accord with requirements is effected by changes to the passage in either a lateral or transverse plane. Air and fuel are received in an intake duct above the venturi throat at which sonic velocity is imparted to the mixture for achieving reduced emission of undesirable pollutants from the engine exhaust. A diffuser extending immediately downstream from the throat efficiently recovers kinetic energy (velocity head) as pressure head and thereby enables sonic velocity at the throat to be maintained over substantially the entire operating range of the engine. Loss of sonic velocity through the throat occurs at low manifold vacuums (high absolute pressure) and is termed the unchoke point.

While the device of CR-l has been found to operate exceedingly well in meeting automotive emission stan dards established by governmental codes, some difficulty has been experienced in maintaining optimum engine performance throughout the operating range, particularly at idle and near idle conditions. Generally speaking, it has been difficult to maintain velocity of the mixture discharging from the diffuser exit to the engine manifold to within about 30 to 500 ft/sec. preferably to within about 100 to about 400 ft/sec. Exit veloci ties lower than minimum tend to correlate with recirculation and agglomeration of fuel drops in the diffuser while velocities higher than maximum tend to correlate with undesirable impaction of fuel drops in the intake manifold. In either direction away from the recommended range. degradation of mixture becomes increasingly worse resulting in a reduction in emission benefits.

Variation of flow area through the device of CR-l from idle to full throttle has generally been by lateral displacement of one or both mirror-like jaws of fixed length defining the venturi passage. In that arrange ment, passage spacing at the venturi throat reduces at idle to an extremely narrow gap of high aspect ratio. For a 350 CID engine, the typical idle gap in that arrangement has been on the order of about O.()l5 to 0.025 inches as compared to the gaps at wide open throttle (WOT) of between about 0.4 to 0.5 inches. Hence, with a constant diffuser length, i.e., measured from the throat to the exit plane in the direction of flow, the ratio of diffuser length to gap width is substantially greater at idle than at WOT. At the same time, area ratio between the exit and throat planes of the device is substantially increased at idle. Because area ratio increases with decreased throttle opening, a decreasing terminal velocity of the discharge mixture occurs at the exit plane from several hundred feet-second to under ft/sec. and even less than 30 ft/sec. at idle. Conversely, a diffuser sized for idle operation can render the exit plane discharge velocity at WOT exceedingly high as the area ratio decreases toward l:l.

Apparatus for overcoming the above mentioned deficiencies associated with changes in area ratio is disclosed in cross referenced application CR2. As disclosed therein, area ratio control in one form is achieved by apparatus operative to selectively vary the diffuser angle between the opposing jaw faces. Area ratio control in another form is achieved by apparatus operative to effect a localized passage opening at idle of selectively different aspect ratio than the as, ect ratio defined over the full longitudinal extent of the jaw faces. In general, both embodiments are generally characterized either by planar movement involving one or both jaws or pivoting one or both jaws in more or less symmetrical relation.

SUMMARY OF THE INVENTION This invention relates to improvements for operation of a variable venturi apparatus supplying an air-fuel mixture through a venturi passage between opposing jaws to an internal combustion engine. More specifically, the invention relates to improvements to apparatus ofa type disclosed in both cross referenced applications CR-l and CR-2 whereby to afford enhanced performance throughout the complete operating range without the attendant growth of fuel drops or impaction of fuel drops previously associated therewith at idle and WOT, respectively. This is obtained in accordance herewith by a double asymmetric pivoting of the jaws concomitantly about their respective axes. Pivoting a first jaw on an axis contiguous to or in the vicinity of the exit plane causes that jaw to operate in a substantially lateral direction for controlling throat area sub stantially independent of the second jaw. Causing the secondjaw to concomitantly pivot about an axis contiguous to or in the vicinity of the throat plane operates in a substantially lateral direction to control exit area substantially independent of the first jaw. By appropri ate selection of kinematic operators, any predetcn mined area ratio or change in area ratio can be preset throughout the operating range of the device.

It is therefore an object of the invention to effect enhanced operation with a variable venturi apparatus supplying an air-fuel mixture to an internal combustion engine.

It is a further object of the invention to effect the pre vious object with a novel construction able to achieve enhanced operation without sacrifice in performance from idle to full throttle operating conditions of the device.

It is a still further object of the invention to effect the foregoing objects by controllably varying exit velocity of the discharging air-fuel mixture to within a predetermined range in which the fuel droplet size formed by the device can be preserved for supply to the engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an isometric representation of an air fuel de vice in accordance herewith for supplying a combustible mixture to an internal combustion engine;

FIG. 2 is a diagrammatic representation of the appa ratus of the invention;

FIGS. 3 and 4 are relative idle and WOT positions,

respectively. utilizing one form of operating mechanism;

FIG. 5 is a sectional view taken substantially along the lines 5-5 of FIG. 3; and

FIGS. 6 and 7 are relative idle and WOT positions, respectively, utilizing a second form of operating mechanism.

Reference is now made to the drawings and particularly to FIG. I in which there is shown a mixing and modulating apparatus 10 of a type more completely disclosed in co-pending patent application CR-l. The apparatus is supported on an intake manifold 12 of an internal combustion engine 14. Air for combustion is drawn from the ambient environment for mixing with liquid fuel supplied via conduit I6 from an automotive fuel tank (not shown). Conduit 16 in turn connects to a fuel bar I8 from which fuel is discharged into the in duced air flow.

Apparatus I0, insofar as it relates to the invention hereof, can be understood with reference to the schematic representation of FIG. 2. As shown therein, apparatus It) is comprised of two opposed jaws 20 and 22 between which is defined a venturi flow passage 24. Air and fuel are received in an intake 26 from which the mixture passes through throat constriction 28 of width H, into diffuser 30 having half angles a and B measured from the vertical. From the diffuser, the mixture discharges into the engine manifold at the diffuser termination or exit 32 of width H Engine demand is accom modated by operatively displacing jaws 20 and 22, will be described, in approaching idle and WOT, respectively. Displacement movement is correlated to maintain sonic velocity past throat 28 for reasons more fully explained in co-pending application CR-l. For those purposes. jaw 20 is supported for pivotal displacement about the axis of a pin shaft 34 located in or near the plane of throat 28 juxtaposed to the surface wall of passage 24. At the same time, jaw 22 is supported for pivotal displacement about the axis of a pin shaft 36 similarly located relative to exit plane 32 and the passage \vall thereat. In this arrangement, there fore, the pi\ot shafts 34 and 36 are located on the oppositc jaw members longitudinally displaced a distance L in the direction of flow.

With a passage 24 of substantially fixed length throughout its height, and a constant velocity (sonic) past throat 28, velocity of the mixture at exit 32 for any given setting (ignoring extraneous factors) can be related to the ratio of passage exit area (Aep) at 32 to passage throat area (At) at 28. Where length is common, the ratio of Aep/At for any given displacement setting can be defined directly in terms of their relative widths. For isentropic flow, exit velocity \"e (fps) at 32 is related to the area ratio Aep/At in a manner well known by those familiar with the fluid mechanics of compressible flow.

Controlling the flow area while maintaining the desired area ratio Aep/At involves cooperative correlation in pivotal displacement of the respective jaws in being moved from the positions shown in solid to that shown in phantom. By these means, pivoting jaw 20 clockwise about axis 34 causes diffuser wall 38 to incur an increased angle B increasing the exit plane width H,/ without affecting or significantly affecting throat width H,. Pivoting jaw 22 clockwise concomitantly therewith about axis 36 causes its diffuser wall 40 to incur an increased angle a increasing the throat width H while per se not affecting or significantly affecting width H, at exit plane 32. Jaw displacement in this manner changes area ratio pursuant to the following formula:

I. l Wan B l W Ttan n As the throat opening is decreased from WOT a will increase while B will decrease, thereby keeping the area ratio within the desired bounds. At idle, a will have its maximum value and B may even be negative if is desired Throughout the operating range of the engine, rotating the jaw members about their respective axes in any predetermined correlation enables corresponding correlation to be maintained between width changes at throat plane 28 and at exit plane 32. By virtue of such control, the area ratio is similarly controlled thereby ensuring discharge ve locity of supplied mixture to within prescribed limits. This relationship can be plotted on a nomograph from which an operating line can be determined that provides the desired change in area ratio over full operating range. Obtainable therefrom are angles 0: and B at all operating points which can be used as a basis for linkage design.

For the operative kinematic embodiment of FIGS. 3 and 4, jaw 20 includes a follower 42 keyed at 44 to shaft 34 and connected to a tension spring 46 tending to urge the follower and jaw in a counterclockwise direction. Engaging follower 42 is a cam 50 keyed at 52 to shaft 36. Also connected to shaft 36 is a sector arm 48 (FIG. 1 in solid) that rotatably operates pivot 36 via the throttle linkage of the automobile. In this manner. rotation of pi\ot 36 clockwise (as illustrated) directly causes jaw 22 to decrease angle a while relatively displaced engagement between cam 50 and follower 42 causes jaw to increase angle B. By appropriate design of cam face 54, a pitch can be selected to maintain any predetermined correlated ratio of angular displacement between the jaw members.

For the operative kinematic embodiment of FIGS. 6 and 7, sector arm 48' (FIG. 1 in phantom) operates a cross shaft 56 keyed at 58 to the vertical cross arm 60 of a pantograph mechanism 62. Comprising the pantograph is a top bar 64 hinged at 66 to bar 60 and at 68 to jaw 22. At the same time, a lower bar 70 is con nected to bar 60 at hinge 72 and hinge 74 is connected to a vertical bar 76 which in turn is fixedly connected to the underside ofjaw 20. From angular displacement of cross shaft 56 via the throttle linkage and sector arm 48'. pantograph 62 effects displacement ofjaws 20 and 22 in a manner analogous to that described for the pre vious embodiment.

By the above description there has been disclosed novel apparatus for supplying air fuel mixtures to an internal combustion engine through a variable venturi device able to control and/or maintain the area ratio between the throat and exit planes of the device in any predetermined relation. Relative pivoting of the jaws enables discharge velocity at the engine manifold to be simply and accurately maintained within preferred limits of operation with a minimum of structural complexity. With discharge velocity being controlled in the manner hereof, undesirable impaction or conglomeration of fuel droplets can be readily avoided for enhancing engine operation with a mechanism of which the operative components are caused to incur only a pivotal motion throughout the operating range of the en gine. The mechanism affords a high degree of accuracy yet lends itself to reliable fabrication within the framework of mass production manufacture.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustrative and not in a limiting sense.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

L In a liquid fuel and intake air mixing and modulating device for supplying a combustion mixture to an internal combustion engine as a high velocity air stream incurring sonic velocity over most of the operating range of the engine to which it is supplied by efficient kinetic energy conversion of the air stream to static pressure and including a housing; oppositely positioned members within said housing defining by their walls a venturi flow passage intervening therebetween; fuel intake means to receive quantities of liquid fuel to be introduced in a substantially uniform pattern into said passage; pivot support means for supporting said opposite members including a first pivot means supporting one of said members for rotational pivot thcreabout and a second pivot means longitudinally displaced downstream from said first pivot means supporting the other of said members for rotational pivot thereabout, and operative means effective to concomitantly pivot both of said members about their respective pivot means in the same rotational direction for varying the flow area of said passage in correlation to operating demands imposed upon the engine while simultaneously maintaining the area ratio between the exit plane of said passage and the throat plane of said passage to within a predetermined range.

2. In a liquid fuel and intake air mixing and modulating device according to claim 1 in which said first pivot means is located to enable its supported member when pivoting to vary the throat area of said passage without significantly affecting the exit area of said passage and said second pivot means is located to enable its supporting member when pivoting to vary the exit area of Said passage without significantly affecting the throat area of said passage.

3. In a liquid fuel and intake air mixing and modulating device according to claim 2 in which said first pivot means is located on a first member juxtaposed to the passage defining wall substantially at the exit plane thereof and said second pivot means is located on the other member juxtaposed to the passage defining wall substantially at the throat plane thereof.

4. In a liquid fuel and intake air mixing and modulating device according to claim 3 in which the area of said exit plane through the pivoting range of said other member is a function of the tangent of an angle B defined by the wall of said other member between its throat plane and its exit plane and its intersection with a plane parallel to the longitudinal flow axis of said passage.

5. In a liquid fuel and intake air mixing and modulating device according to claim 3 in which the area of said throat plane through the pivoting range of said first member is a function of the tangent of an angle a defined by the wall of said first member between its throat plane and its exit plane and its intersection with a plane parallel to the longitudinal flow axis of said passage.

6. In a liquid fuel and intake air mixing and modulating device according to claim 5 in which angle a increases and decreases inversely with increase and decrease of the passage flow area past said throat plane.

7. In a liquid fuel and intake air mixing and modulating device according to claim 6 in which the area of said exit plane (Aep) is maintained proportional to the area of said throat plane (At) as defined substantially by the formula L Acp 1 [In an B l tan a where L =separation between the axes of said first and second pivot means measured parallel to the flow axis of said passage Ho separation between the throat wall of one member and the exit wall of the other member mea sured transversely to the flow axis of said passage. 8. In a liquid fuel and intake air mixing and modulating device according to claim 3 in which said operative means includes a linkage adapted to be actuated by the throttle linkage of an internal combustion engine with which said device is to be utilized.

9. In a liquid fuel and intake air mixing and modulating device according to claim 8 in which said linkage 7 8 comprises :1 pantogruph operably connected to said includes a cam secured on one of said pivot means and first and other members. a follower operubly engaging said cum and secured on 10. In a liquid fuel and intake air mixing and moduthe other of said pivot means. hating device according to claim 8 in which said Iinkugc 

1. IN A LIQUID FUEL AND INTAKE AIR MIXING AND MODULATING DEVICE FOR SUPPLYING A COMBUSTION MIXTURE TO AN INTERNAL COMBUSTION ENGINE AS A HIGH VELOCITY AIR STREAM INCURRING SONIC VELOCITY OVER MOST OF THE OPERATING RANGE OF THE ENGINE TO WHICH IT IS SUPPLIED BY EFFICIENT KINETIC ENERGY CONVERSION OF THE AIR STREAM TO STATIC PRESSURE AND INCLUDING A HOUSING, OPPOSITELY POSITIONED MEMBERS WITHIN SAID HOUSING DEFINING BY THEIR WALLS A VENTURI FLOW PASSAGE INTERVENING THEREBETWEEN, FUEL INTAKE MEANS TO RECEIVE QUANTITIES OF LIQUID FUEL TO BE INTRODUCED IN A SUBSTANTIALLY UNIFORM PATTERN INTO SAID PASSAGE, PIVOT SUPPORT MEANS FOR SUPPORTING SAID OPPOSITE MEMBERS INCLUDING A FIRST PIVOT MEANS SUPPORTING ONE OF SAID MEMBERS FOR ROTATIONAL PIVOT THEREABOUT AND A SECOND PIVOT MEANS LONGITUDINALLY DISPLACED DOWNSTREAM FROM SAID FIRST PIVOT MEANS SUPPORTING THE OTHER OF SAID MEMBERS FOR ROTATIONAL PIVOT THEREABOUT, AND OPERATIVE MEANS EFFECTIVE TO CONCOMITANTLY PIVOT BOTH OF SAID MEMBERS ABOUT THEIR RESPECTIVE PIVOT MEANS IN THE SAME ROTATIONAL DIRECTION FOR VARYING THE FLOW AREA OF SAID PASSAGE IN CORRELATION TO OPERATING DEMANDS IMPOSED UPON THE ENGINE WHILE SIMULTANEOUSLY MAINTAINING THE AREA RATIO BETWEEN THE EXIT PLANE OF SAID PASSAGE AND THE THROAT PLANE OF SAID PASSAGE TO WITHIN A PREDETERMINED RANGE.
 2. In a liquid fuel and intake air mixing and modulating device according to claim 1 in which said first pivot means is located to enable its supported member when pivoting to vary the throat area of said passage without significantly affecting the exit area of said passage and said second pivot means is located to enable its supporting member when pivoting to vary the exit area of said passage without significantly affecting the throat area of said passage.
 3. In a liquid fuel and intake air mixing and modulating device according to claim 2 in which said first pivot means is located on a first member juxtaposed to the passage defining wall substantially at the exit plane thereof and said second pivot means is located on the other member juxtaposed to the passage defining wall substantially at the throat plane thereof.
 4. In a liquid fuel and intake air mixing and modulating device according to claim 3 in which the area of said exit plane through the pivoting range of said other member is a function of the tangent of an angle Beta defined by the wall of said other member between its throat plane and its exit plane and its intersection with a plane parallel to the longitudinal flow axis of said passage.
 5. In a liquid fuel and intake air mixing and modulating device according to claim 3 in which the area of said throat plane through the pivoting range of said first member is a function of the tangent of an angle Alpha defined by the wall of said first member between its throat plane and its exit plane and its intersection with a plane parallel to the longitudinal flow axis of said passage.
 6. In a liquid fuel and intake air mixing and modulating device according to claim 5 in which angle Alpha increases and decreases inversely with increase and decrease of the passage flow area past said throat plane.
 7. In a liquid fuel and intake air mixing and modulating device according to claim 6 in which the area of said exit plane (Aep) is maintained proportional to the area of said throat plane (At) as defined substantially by the formula
 8. In a liquid fuel and intake air mixing and modulating device according to claim 3 in which said operative means includes a linkage adapted to be actuated by the throttle linkage of an internal combustion engine with which said device is to be utilized.
 9. In a liquid fuel and intake air mixing and modulating device according to claim 8 in which said linkage comprises a pantograph operably connected to said first and other members.
 10. In a liquid fuel and intake air mixing and modulating device according to claim 8 in which said linkage includes a cam secured on one of said pivot means and a follower operably engaging said cam and secured on the other of said pivot means. 